Rock breaking machine

ABSTRACT

A device for mounting a rock breaking or like impact tool on, for example the jib of an earth working machine, comprises a cradle having means whereby it may be attached to such a jib, a carriage for the tool, means supporting said carriage in the cradle and arranged to permit a limited degree of oscillation or reciprocation of the carriage in the direction of oscillation or reciprocation of the tool, and means operative to cushion or damp such oscillation or reciprocation of the carriage. In one preferred embodiment of the invention the frequency of the damping or cushioning material differs from the operating frequency of the tool. Conveniently the damping or cushioning material has a hysteresis characteristic.

United States Patent 1 Sumner June 17, 1975 [54] ROCK BREAKING MACHINE 2,762.66] 9/!956 Sloyan 248/22 t B S ne Rainford, En land [75] or an um Primary Examiner.lames A. Leppink AsislgmifiI g h l g Attorney, Agent, or Firm-Berman, Bishoff & Platt otting ams ire. ng an [22] Filed: Jan. 25, I974 57 ABSTRACT '1 PP N01 436,635 A device for mounting a rock breaking or like impact tool on, for example the jib of an earth working ma- [30] Foreign Application Priority Data chine, comprises a cradle having means whereby it F b 17 1973 United Kin dom 792" may be attached to such a jlb, a carriage for the tool. e g means supporting said carriage in the cradle and arranged to permit a limited degree of oscillation or re- 3 173/139 gfgjiggg ciprocation of the carriage in the direction of oscilla- 299/69 tion or reciprocation of the tool, and means operative l 0 re HIS/20 to cushion or damp such oscillation or reciprocation of the carriage. In one preferred embodiment of the invention the frequency of the damping or cushioning [56] References cued material differs from the operating frequency of the UNITED STATES PATENTS tool. Conveniently the damping or cushioning material 1,390,834 9/l92l Stage 173/]39 has a hysteresis characteristic 2,269.033 1/1942 Morrison et al. i [73/162 2,423,787 7/1947 Mosena et al. l73/l62 5 Claims, 4 Drawing Figures PATENTEDJUN 1 7 I975 //////////////////V/////U//////fl/7////////U/////l -Fl Gin- ROCK BREAKING MACHINE This invention is for improvements in or relating to excavating machines, rock breaking machines and the like.

One particular application of the invention is to a mobile excavating machine of the kind having a manoeuvreable jib which normally carries an excavating bucket at its forward end. An object of the present in vention is to make it possible, as and when desired, to substitute a rock breaking tool for said excavating bucket. The rock breaking tool may, for example, be of the character described and claimed in the specification of our U.S.A. application for Patent, Ser. No. 218,671 dated Jan. l8, l972.

According to the present invention there is provided a mounting, for a rock breaking or like impact tool, which mounting is permitted a limited degree of oscillation or reciprocation in the direction of oscillation of the tool and wherein means is provided for cushioning or damping such oscillation of the mounting.

According to a further feature of the invention there is provided a mounting for a rock breaking or like impact tool having at least two relatively movable members and cushioning or damping means therebetween to allow a limited degree of oscillation or reciprocation in the direction of oscillation or reciprocation of the tool.

Preferably the frequency of the damping material differs from that of the operating frequency of the impacting tool. In one preferred embodiment the frequency of the damping material is lower than the operating frequency of the tool. With such an arrangement substantially no vibration build-up occurs.

The cushioning or damping action allows the jib and other parts of a normal excavating machine to withstand the stresses created by the operation of the impact tool.

Conveniently the cushioning or damping means has a non-linear characteristic so that the resistance to oscillation of the mounting increases with the degree of compression of said cushioning or damping means.

It is also believed to be preferable that the cushioning or damping means should have a hysteresis characteristic, i.e., that there should be a lag between the releasing of stress and cessation of strain in the cushioning or damping means.

In one preferred embodiment of the invention the cushioning or damping means comprises a cushion or a series of neighbouring cushions of compressed, woven or interlinked steel wires or springs. Such shock absorbing cushions are available under the Trade Mark VIBRASHOCK.

Preferably the cushioning or damping means is subjected to a degree of pre-compression.

Conveniently there is a cushioning or damping means arranged on opposite sides of a member which oscillates with the mounting.

One particular embodiment of the invention wiil now be described, by way of example, with reference to the accompanying semi-diagrammatic drawings in which:

FIG. 1 shows a fragment of the jib or angularly movable arm of an excavating machine provided at its forward end with an impact tool suitable for rock breaking or similar operations,

FIG. 2 is a sectional side elevation on the line II-II of FIG. 3 of the mounting arrangement for the impact tool,

FIG. 3 is a rear elevation of the mounting arrangement detached from the arm of the excavating ma chine, and

FIG. 4 is a sectional elevation on the line IVIV of FIG. 3.

Referring to FIG. 1 of the drawings, the reference numeral 10 indicates a fragment of the jib or angularly movable arm of the excavating machine.

For the purpose of the present invention the forward end of the arm 10 is provided with a cradle 11 in which the impact rock breaking tool 12, which includes a chisel 12a, is mounted. The cradle 11 is attached to the forward end of the arm I0 by brackets 13 pivotally connected to the arm at 14. The arrangement is such that the cradle can be angled about the pivot 14 by means of a hydraulic ram and lever arrangement (not shown) connected to the brackets at 15 by links 16. The arm itself is also manoeuvreable after the manner of the jib or arm of an excavating machine.

The mounting in the cradle 11, for the rock breaking tool, comprises (see FIGS. 2, 3 and 4) a base plate or platform 17 fixed on parallel tubular shafts l8 slidable to a limited extent in bearings I9 carried by the cradle.

Two parallel rods 20 (see FIGS. 3 and 4) are secured to the cradle 11 as indicated at 2] and extend slidably through bushes 22 mounted in a bracket or brackets 23 depending from and secured to the underside of the base plate or platform 17.

A series of shock absorbing cushions 24 are assembled on the rods 20 between abutments 25, secured to the rods 20, and the bushes 22. A similar series of shock absorbing cushions 24 are assembled on the rods between the bushes 22 and an abutment plate or plates 26 on the rods 20. The rods 20 are screw-threaded as indicated at 27 and provided with nuts 28 so that a degree of pre-compression can be applied to the shock absorbing cushions 24 through the abutment plate or plates 26.

The cushions 24 are stainless steel resilient wire cushions, in the form of rings, available under the Trade Mark VIBRASHOCK. Other cushioning or damping means may, however, be used for the purpose of the in vention.

It will be understood that when the impact rock breaking .tool 12 is in operation its supporting base plate or platform 17 can oscillate to a limited extent in the bearings 19 and the stresses created by the impact tool are cushioned or damped, by the shock absorbing cushions 24, before being transmitted to the cradle 11 and thence to the jib 10 and other parts of the machine.

The cushions or shock absorbing rings 24 have a hysteresis characteristic, i.e., there is a lag between the releasing of stress and cessation of strain. This is believed to be advantageous.

I claim:

I. In combination a reciprocating rock-breaking impact tool and means for mounting said impact tool on a rock-breaking machine, said mounting means comprising a cradle having means for attaching it to an arm of a rock-breaking machine, guide means located in and carried by said cradle and extending in the direction of reciprocation of the impact tool, a base plate, for the impact tool, slidably mounted on said guide means, a bracket on said base plate, rod means located in and carried by the cradle and extending in the direction of reciprocation of the impact tool and passing freely through said bracket, abutment means and a series of shock absorbing cushions assembled on said rod means and held between said abutment means and said bracket thereby to control and damp oscillation of the impact tool during operation thereof.

2. The combination claimed in claim 1 wherein there is a series of said shock absorbing cushions between said bracket and abutment means fixed at opposite ends of said rod means.

3. The combination claimed in claim 1 wherein sion of the cushions, and a hysteresis characteristic. 

1. In combination a reciprocating rock-breaking impact tool and means for mounting said impact tool on a rock-breaking machine, said mounting means comprising a cradle having means for attaching it to an arm of a rock-breaking machine, guide means located in and carried by said cradle and extending in the direction of reciprocation of the impact tool, a base plate, for the impact tool, slidably mounted on said guide means, a bracket on said base plate, rod means located in and carried by the cradle and extending in the direction of reciprocation of the impact tool and passing freely through said bracket, abutment means and a series of shock absorbing cushions assembled on said rod means and held between said abutment means and said bracket thereby to control and damp oscillation of the impact tool during operation theReof.
 2. The combination claimed in claim 1 wherein there is a series of said shock absorbing cushions between said bracket and abutment means fixed at opposite ends of said rod means.
 3. The combination claimed in claim 1 wherein means is provided for adjusting a degree of pre-compression of the shock absorbing cushions.
 4. The combination claimed in claim 1 wherein the shock absorbing cushions comprise compressed, interlinked steel springs.
 5. The combination claimed in claim 4 wherein said cushions have a frequency which differs from the operating frequency of the impact tool, a non-linear characteristic, so that the resistance to oscillation of the mounting means increases with the degree of compression of the cushions, and a hysteresis characteristic. 